I'd set up a SQL Agent job scheduled for whatever time you need this to happen.

One step that executes:

USE <database_name>;

BEGIN

ALTER DATABASE <database_name> SET SINGLE_USER WITH ROLLBACK IMMEDIATE;

ALTER DATABASE <database_name> SET MULTI_USER;

END

Quick and dirty, but it works.

I've also seen an approach that kills sessions in a loop based on the output of sp_who2, but its a complete pita if you have an app that wants to maintain a connection.